arch: disambiguate $(( in arch-syscall-validate

shellcheck complains:

> In arch-syscall-validate line 785:
> 	sc_list=$((for abi in $abi_list; do
>                 ^-- SC1102 (error): Shells disambiguate $(( differently or not at all. For $(command substitution), add space after $( . For $((arithmetics)), fix parsing errors.

Another tool, shfmt, can't even parse the file:

> arch-syscall-validate:785:17: not a valid arithmetic operator: abi

Add a space to resolve this.

Signed-off-by: Kir Kolyshkin <[email protected]>
Acked-by: Paul Moore <[email protected]>
Signed-off-by: Tom Hromatka <[email protected]>

src/arch-syscall-validate

@@ -782,9 +782,9 @@ function gen_csv() {
  eval output_$abi=$(mktemp -t syscall_validate_XXXXXX)
  dump_$2_$abi "$1" > $(eval echo $`eval echo output_$abi`)
  done
- sc_list=$((for abi in $abi_list; do
+ sc_list=$( (for abi in $abi_list; do
  cat $(eval echo $`eval echo output_$abi`);
- done) | awk -F "," '{ print $1 }' | sort -u)
+  done) | awk -F "," '{ print $1 }' | sort -u)
 
  # redirect the subshell to the csv file
  (